Such a mower is known in which the bearing by which the strut of the support structure is connected to the shaft of the outboard cutting element located at the corresponding end of the cutting bar which is guided in the housing of the cutting bar by two roller bearings consists of a self-aligning roller bearing. In this known mower, the strut of the support structure is rigidly connected to one of the ends of the beam of the support structure. At its other end, the beam of the support structure is connected to a transmission device which extends above the cutting element placed at the corresponding end of the cutting bar and called the inboard cutting element. The shaft of the inboard cutting element, which is also guided in rotation in the housing of the cutting bar, is extended upwardly and penetrates into the transmission device, where it is guided in rotation by two other roller bearings. This shaft serves to drive the inboard cutting element and to transmit the movement from the transmission device to the drive elements housed on the inside of the housing of the cutting bar and serving to drive in rotation the following cutting elements. The shaft also serves to connect the housing of the cutting bar to the transmission device, just like the shaft of the outboard cutting element which serves to connect the housing to the strut of the support structure.
The known mower has drawbacks.
A first drawback of the known mower relates to the unequal distribution of the absorption of forces and shocks exerted on the housing during work. During work, the housing of the mower slides over the ground. Consequently, it is subjected to a force of resistance to advance which is directed horizontally from the front to the back and which varies continuously, since the terrain on which the mower operates is never rigorously plane. This force even at times is transformed into shocks when the housing encounters an obstacle on the ground. Now, since the end of the cutting bar where the strut of the support structure extends is connected to the strut by means of a self-aligning roller bearing, the moment which tends to make the housing of the cutting bar pivot backwardly, produced by this force of resistance to advance and the shocks in case of encountering an obstacle, is absorbed entirely by the roller bearings guiding the shaft of the first cutting element extending under the transmission device and which penetrates inside the transmission device. As a result, the roller bearings have a relatively short life.
A second drawback of the known mower resides in the difficulty of mounting the support structure on the cutting bar. The housing of the cutting bar is made from bent sheet metal, while the support structure is made by welding. It follows that the necessary production tolerances must be relatively large. Further, these elements can exhibit a certain initial deformation. Thus, during mounting of the support structure on the cutting bar, it is necessary to deform the cutting bar (which is the more flexible element) so that, from the beginning, not inconsiderable stresses are introduced into the roller bearings that guide in rotation the shafts of the end cutting elements.
This known mower also has a third drawback. The self-aligning bearing and a part of the strut of the support structure extend on the inside of a drum placed above the outboard cutting element. The self-aligning bearing, which connects the shaft of the outboard cutting element and of the drum to the strut, requires a relatively large space between the upper face of the drum and the strut. Plant debris and dust can thus be introduced inside the drum. When the mass of plant debris and dust becomes great, imbalances are produced which increase the load on the self-aligning bearing. Further, frictions are produced which heat the self-aligning bearing so that its life is considerably shortened.
Another mower is known the support structure of which is provided with two struts located on each of its ends. These struts extend downwardly in the direction of the cutting elements extending at the corresponding ends of the cutting bar. These struts are each connected to the shafts of end cutting elements which are guided in the housing of the cutting bar by two roller bearings by means of a bearing having two roller bearings with an axis of rotation merged with the axis of the shaft of the corresponding cutting elements. The shaft of each end cutting element extends to the level of the beam of the support structure, where it engages by means of gears with a drive shaft guided in rotation inside of the beam of the support structure. The shafts of the end cutting elements serve to drive in rotation their cutting element and, additionally, a certain number of the following cutting elements thanks to driving elements housed on the inside of the housing of the cutting bar. Simultaneously these shafts also serve to connect the housing of the cutting bar to the support structure.
This other known mower also has drawbacks.
A first drawback of this known mower also resides in the difficulty in mounting the support structure on the cutting bar. Considering the relatively large production tolerances required by the methods of production of the cutting bar and support structure, it is also necessary to deform the cutting bar (which is the most flexible element) to be able to cause the axes of the shafts of the end cutting elements guided in the struts of the support structure to correspond with the axes of the bearings of the cutting bar in which the ends of the shafts of the end cutting elements are supposed to penetrate.
A second drawback of this other known mower resides in the extremely great stresses which the roller bearings, which guide the shafts of the end cutting elements in rotation, are made to absorb during work. As with the first known mower, during work the housing of the cutting bar slides on the ground, which exhibits more or less great unevennesses. This leads to forces directed upwardly on the housing of the cutting bar which cause bending of the housing. During this bending, the housing pulls on the ends of the shafts of the end cutting elements with a very substantial force, considering the direction of this force in relation to the direction of the forces that generate it. This very substantial force is absorbed entirely by the roller bearings which guide the shafts of the end cutting elements in rotation. Consequently, the roller bearings also have a relatively short life.
The mowers of the prior art thus cause very high repair costs for the farmers, who do not accept them easily. In addition, if the roller bearings break during the season, they can lose a great part (even all) of their harvest, which would be a catastrophe for many of them.